Port structure in semiconductor processing system

ABSTRACT

In a port structure  16 A in a semiconductor processing system  2 , a door  20 A is disposed in a port  12 A defined by upright wall  52  and  54 . A table  48  opposed to the port is disposed outside the system. Defined on the table is a mount region  76  for mounting an open type cassette  18 A for a process subject substrate W. A hood  50  is disposed rotatable relative to the table. The hood defines in its closed position a closed space surrounding the mount region and port, the space having a size to receive the cassette. First ventholes  58  are formed in the upright walls and/or the door so as to introduce gas from within the system into the closed space in the hood. Second ventholes  72  are formed in the table so as to discharge the gas can be discharged out of the closed space.

FIELD OF THE INVENTION

The present invention relates to a port structure for loading andunloading a substrate to be processed into and from a semiconductorprocessing system. The term semiconductor processing used herein denotesvarious processes performed to manufacture a semiconductor device or astructure connected to a semiconductor device, e.g., wiring andelectrodes, on a substrate to be processed such as a semiconductor waferor an LCD substrate by way of forming a semiconductor layer, aninsulating layer, a conductive layer and the like on the substrate to beprocessed into a specified pattern.

BACKGROUND OF THE INVENTION

In order to manufacture a semiconductor integrated circuit, variousprocesses such as film forming, etching, oxidation and diffusion areperformed on a wafer. In such processes, a throughput and a yield arerequired to be improved along with the trend of miniaturization and highintegration of the semiconductor integrated circuit. From this point ofview, a semiconductor processing system known as a so-called clustertool has been developed, wherein a plurality of processing apparatusesperforming a same process or a plural number of processing apparatusesperforming different processes are connected with one another via acommon transfer chamber such that various processes can be successivelyexecuted without exposing a wafer to the atmosphere. A cluster tool typesemiconductor processing system is disclosed in, e.g., Japanese PatentLaid-open Publication Nos. 2000-208589 and 2000-299367.

As for such a processing system, there is a type in which a portstructure for mounting a cassette with semiconductor wafers is disposedat a front end thereof. A wafer in the cassette is carried into thesystem by a transfer arm and then loaded into a load-lock chambercapable of controlling a pressure to be set at a level between thevacuum and the atmospheric pressure. Next, the wafer is loaded into acommon vacuum transfer chamber whose peripheral portions are connectedto a plurality of vacuum processing apparatuses and then sequentiallyloaded into each of the vacuum processing apparatuses surrounding thecommon transfer chamber located at the center to thereby undergocontinuous processes. Further, a processed wafer returns to a primarycassette along, e.g., a primary path.

In general, in a facility in which a semiconductor processing system isinstalled, an atmosphere of clean air is maintained at a predeterminedlevel of cleanliness. Further, in the processing system, a chamber intowhich the wafer is introduced maintains an atmosphere of clean air at ahigher level of cleanliness in order to more completely preventparticles from being introduced into a succeeding load-lock chamber andthe like.

A cassette itself has a closed structure or an open structure dependingon a wafer size. For example, in case of a cassette for 300 mm wafers,the cassette itself has a closed structure (closed type cassette). Insuch case, when the wafer is loaded thereinto, a cover of an opening ofthe cassette is removed, and an operation is performed while keeping theopening close to a port of the processing system (see, e.g., JapanesePatent Laid-open Application No. 1999-145245). Accordingly, a highlystable loading operation can be performed.

Meanwhile, in case of a cassette for, e.g., 200 mm wafers, the cassetteitself has an open structure (open type cassette). In this case, it ispreferable to separate the cassette from an operator in order to performthe loading operation safely.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide acompact and highly stable port structure in a semiconductor processingsystem, which is capable of avoiding a contamination of a wafer.

In accordance with a preferred embodiment of the present invention,there is provided a port structure for loading and unloading a substrateto be processed into and from a semiconductor processing system, whereinan inside of the system is set to have a positive pressure compared toan outside thereof by a gas supply, the port structure including: abulkhead for partitioning the inside and the outside of the system andhaving a port for passing therethrough the substrate to be processed; adoor for opening and closing the port; a table disposed outside thesystem to face the port, wherein the table is provided with a mountregion for mounting thereon an open cassette accommodating therein aplurality of substrates to be processed in multi-levels; a hoodrotatably disposed between a closed position and an open position withrespect to the table, wherein the hood at the closed position forms,together with the bulkhead and the table, a closed space surrounding themount region and the port, the closed space having a size to accommodatetherein the cassette mounted on the mount region, and the hood at theopen position exposes the mount region; a driving unit for rotating thehood; first ventholes formed through at least one of the bulkhead andthe door so as to introduce the gas from the inside of the system intothe closed space; and second ventholes formed through the table so as todischarge the gas out of the closed space.

In accordance with another preferred embodiment of the presentinvention, there is provided A port structure for loading and unloadinga substrate to be processed into and from a semiconductor processingsystem, including: a bulkhead for partitioning an inside and an outsideof the system and having a port therethrough for passing the substrateto be processed; a door for opening and closing the port; a tabledisposed outside the system to face the port, wherein the table isprovided with a mount region for mounting thereon an open cassetteaccommodating therein in multi-levels a plurality of substrates to beprocessed; a transparent hood rotatably disposed between a closedposition and an open position with respect to the table, wherein thehood at the closed position forms, together with the bulkhead and thetable, a closed space surrounding the mount region and the port, theclosed space having a size to accommodate therein the cassette mountedon the mount region, and the hood at the open position exposes the mountregion; and a driving unit for rotating the hood, wherein the table hasa slit for passing the rotating hood therethrough, and the hood islocated under the table while in an open position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view showing a semiconductor processingsystem having a port structure in accordance with a preferred embodimentof the present invention;

FIG. 2 shows a sectional view illustrating an inlet side transferchamber of the processing system shown in FIG. 1 and a port structureattached thereto;

FIGS. 3A and 3B depict sectional views showing a state in which a hoodis in a closed position in the port structure illustrated in FIG. 2;

FIG. 4 provides a sectional view describing a state in which the hood isin an open position in the port structure illustrated in FIG. 2;

FIGS. 5A to 5C present perspective views explaining an opening/closingoperation of the hood in the port structure shown in FIG. 2;

FIG. 6 represents a partially exploded perspective view depicting aninside of the port structure illustrated in FIG. 2;

FIGS. 7A to 7D offer diagrams for explaining an operation of a drivingunit or a break when the hood is opened or closed in the port structureillustrated in FIG. 2;

FIG. 8 is a side view showing a link mechanism for opening and closingthe hood in the port structure shown in FIG. 2;

FIGS. 9A and 9B respectively provide a side view and a vertical rearview showing a structure of a portion attached to the hood and arotation axis thereof in the port structure illustrated in FIG. 2; and

FIGS. 10A to 10J offer diagrams for schematically explaining anoperational relationship between a sliding door and the hood in the portstructure illustrated in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed. Further, like reference numerals will be given to like partshaving substantially the same functions, and redundant descriptionthereof will be provided only when necessary.

FIG. 1 is a schematic plan view showing a semiconductor processingsystem having a port structure in accordance with a preferred embodimentof the present invention.

As illustrated in FIG. 1, a processing system 2 has a plurality of,e.g., four, processing apparatuses 4A, 4B, 4C and 4D; an approximatelyhexagon shaped common transfer chamber 6; a first and a second load-lockchamber 8A and 8B having a load-lock function; and a narrow and longinlet side transfer chamber 10. The common transfer chamber 6 and thefirst and the second load-lock chamber 8A and 8B are evacuable andairtight chambers.

Specifically, each of the processing apparatuses 4A to 4D is connectedto one of four sides of the approximately hexagon shaped common transferchamber 6, and the first and the second load-lock chamber 8A and 8B areconnected to other two sides thereof, respectively. In other words, theprocessing system 2 has a cluster tool type structure in which theprocessing apparatuses and the load-lock chambers are connected to thecommon transfer chamber 6, which is at a center thereof. The inlet sidetransfer chamber 10 is connected to both the first and the secondload-lock chamber 8A and 8B. The processing apparatuses 4A to 4D and thefirst and the second load-lock chamber 8A and 8B are connected to thecommon transfer chamber 6 via airtightly openable/closable gate valvesG1 to G4, G5 and G6, respectively. The first and the second load-lockchamber 8A and 8B are connected to the inlet side transfer chamber 10via airtightly openable/closable gate valves G7 and G8, respectively.

The four processing apparatuses 4A to 4D are designed in a way that asame process or different processes are performed on a semiconductorwafer W as a substrate to be processed in a vacuum atmosphere. A firsttransfer unit 14 having stretchable, bendable, elevatable and revolvablemulti-joint arms is provided at a position in an inner side of thecommon transfer chamber 6 such that the first transfer unit 14 can havean access therefrom to any of the two load-lock chambers 8A and 8B andthe four processing apparatuses 4A to 4D. The first transfer unit 14 hastwo picks 14A and 14B that are independently stretchable and bendable inopposite directions and, thus, can carry two wafers at a time. Further,the first transfer unit 14 having a single pick can be used.

The inlet side transfer chamber 10 is of a horizontally lengthened boxin which a downflow inert gas such as a N₂ gas or clean air circulates.Formed at one side of the horizontally lengthened box are a single or aplurality of ports (in this embodiment, three) 12A, 12B and 12C forloading and unloading the semiconductor wafer W as a substrate to beprocessed thereinto and therefrom. Port structures 16A, 16B, and 16C forwafer cassettes are disposed correspondingly to the ports 12A to 12C,respectively. Wafer cassettes 18A to 18C can be mounted on the portstructures 16A, 16B and 16C, respectively.

As shown in FIGS. 2 to 4, each of the cassettes 18A to 18C canaccommodate therein a plurality of, e.g., 25, wafers W mounted inmulti-levels at an equal pitch. An inside of each cassette 18A to 18C isof an open structure such that a gas can circulate. The wafer can beloaded into and unloaded from the inlet side transfer chamber 10 viasliding doors 20A, 20B and 20C disposed corresponding to the ports 12Ato 12C, respectively.

Provided in the inlet side transfer chamber 10 is a second transfer unit22 for transferring the wafer W in a length direction thereof. Thesecond transfer unit 22 is slidably supported on a guide rail 24extending in the length direction along a central portion of the inletside transfer chamber 10. The guide rail 24 has therein, e.g., a linearmotor as a moving mechanism, and the second transfer unit 22 moves alongthe guide rail 24 in an X direction by the linear motor.

Disposed at an end portion of the inlet side transfer chamber 10 is anorienter 26 as a positioning mechanism for performing a positioning ofthe wafer. The orienter 26 has a rotatable table 28 rotated by a drivingmotor (not shown) while having the wafer W mounted thereon. Provided atan outer circumferential portion of the rotatable table 28 is an opticalsensor 30 for detecting a peripheral portion of the wafer W. The opticalsensor 30 detects a location/direction or a misalignment of a notch oran orientation flat of the wafer W.

The second transfer unit 22 has two multi-joint shaped transfer arms 32and 34 installed in two vertical steps. Bifurcated picks 32A and 34A areattached to leading ends of the transfer arms 32 and 34, respectively,and a wafer W is directly held on each of the picks 32A and 34A. Each ofthe transfer arms 32 and 34 is stretchable and bendable in a radialdirection, i.e., R direction and the stretching and bending of thetransfer arms 32 and 34 can be individually controlled. Further, thetransfer arms 32 and 34 can be rotatable as a single body in a θdirection, i.e., a revolving direction relative to a base 36.

FIG. 2 shows a sectional view illustrating the inlet side transferchamber 10 of the processing system shown in FIG. 1 and the portstructure 16A attached thereto. As shown in FIG. 2, installed at aceiling portion of the inlet side transfer chamber 10 are a blow fan 38and a filter 40 having, e.g., a ULPA (ultra low penetration air) filter.A clean gas supplied from ventholes 42 formed on a ceiling plate passesthrough the filter 40 and then constantly forms a downflow 44 cleanlymaintained in the inlet side transfer chamber 10. The downflow 44 isdownwardly discharged through ventholes 46 provided at a bottom plate ofthe inlet side transfer chamber 10 to outside of the facility. In thiscase, an inside of the inlet side transfer chamber 10 is set to be in astate of a positive pressure slightly higher than an outer atmosphericpressure by, e.g., 1.3 Pa.

Hereinafter, the port structures 16A to 16C disposed respectively to theports 12A to 12C of the inlet side transfer chamber 10 will bedescribed. Since the three port structures 16A to 16C have a samestructure, a single port structure, e.g., the port structure 16A as anexample will be described herein. Schematically, the port structure 16Aincludes the sliding door 20A installed at the port 12A; a table 48 formounting thereon the cassette 18A; and a hood 50 rotatably installed tofully cover the cassette 18A and the port 12A.

FIGS. 3A and 3B depict sectional views showing a state in which the hood50 is in a closed position in the port structure 16A; FIG. 4 provides asectional view describing a state in which the hood 50 is in an openposition in the port structure 16A; FIGS. 5A to 5C present perspectiveviews explaining an opening/closing operation of the hood 50 in the portstructure 16A; FIG. 6 represents a partially exploded perspective viewdepicting an inside of the port structure 16A.

As illustrated in FIGS. 2 to 4, the port 12A is formed by opening afront panel 52 of the inlet side transfer chamber 10 in an approximatelyquadrangular shape. Disposed at an upper portion of the port 12A is anarrow and long additional panel 54 made of, e.g., aluminum plate fordividing the port 12A. The sliding door 20A for opening and closing theport 12A is slidably installed inside the port 12A. The sliding door 20Avertically moves by an elevation mechanism 56 provided at a lowerportion of the port 12A. The sliding door 20A is formed in a shape of athin plate made of, e.g., aluminum.

Formed on an almost entire surface of the sliding door 20A and theadditional panel 54 is a plurality of first ventholes 58 having adiameter of, e.g., about 4 mm. A gas of a high level of cleanliness inthe inlet side transfer chamber 10 is introduced into the hood 50 in theclosed position via the first ventholes 58. The first ventholes 58 maybe formed on at least one of the sliding door 20A and the additionalpanel 54 but preferably on the sliding door 20A in order to pass the gasof a high level of cleanliness through the cassette 18A as well.

Not just for an open state and a closed state, the sliding door 20Aalways maintains a noncontact state with the additional panel 54 or thefront panel 52. In case of the closed state, a narrow gap 60 in therange from about 0.5 to 1.0 mm is secured between the sliding door 20Aand the additional panel 54. Thus, since the sliding door 20A is kept inthe noncontact state, particles can be prevented from being generated.

The table 48 is installed at an outside of the front panel 52 toward theport 12A, and a mount region for mounting the wafer cassette 18A isformed thereabove. The table 48 is formed of a rectangular top plate ofa supporting housing 70 made of stainless, and a space surrounded bywalls of the supporting housing 70 is formed under the table 48.

A platform 76 forming a cassette mounting region is disposed on thetable 48, specifically, at an approximately central portion of ahorizontal direction thereof and near the port 12A. Disposed on asurface of the platform 76 is a plurality of, e.g., four, positioningblocks 78 for performing a positioning when the cassette 18A is mountedthereon (see FIG. 5). Provided on the platform 76 is a leveling screw(not illustrated) for controlling the top surface to be horizontal.

Disposed at a central portion of the platform 76 is a cassette sensor 80(see FIGS. 3A and 3B) for detecting whether or not there exists thecassette 18A. Provided at an end portion of the platform 76 at the port12A side is a wafer sensor 51 having an optical sensor for transmittingand receiving light. The wafer sensor 51 detects whether or not thewafer W is ejected from the cassette 18A mounted on the table 48.

The hood 50 is rotatably supported at the supporting housing 70 to be ina closed position and an open position. The hood 50 in the closedposition forms a closed space surrounding the platform 76 (cassettemounting region) and the port 12A together with the front panel 52, theadditional panel 54 and the table. The closed space is of a size thatcan accommodate the cassette 18A mounted on the platform 76. The hood 50in the open position exposes the platform 76.

The entire hood 50 is made of a transparent material, e.g., anti-static,transparent polycarbonate resin. As illustrated in FIGS. 5A to 5C, thehood 50 includes an approximately 90 degrees arc shaped front plate 50Aand fan shaped side plates 50B at both sides thereof. An approximatelyquadrangular shaped window 64 for maintenance is detachably attached tothe front plate 50A by screws 62 (see FIGS. 3A and 3B). By separatingthe window 64 from the front plate 50A, maintenance for an inner surfaceof the hood 50 can be performed without removing the hood 50 from thesupporting housing 70.

Formed at the table 48 is a U-shaped slit 68 for passing the hood 50therethrough when the hood 50 rotates. The hood 50 vertically rotatesafter passing through the slit 68 without being in contact therewith.Further, in the closed position, a leading end portion of the hood 50 isin the noncontact state with an opposing portion (the additional panel54 in this embodiment). In other words, a gap 66 of, e.g., a few mm, isformed between the leading end portion of the hood 50 and the additionalpanel 54. Due to such configuration, it is possible to prevent particlesfrom being generated by a contact between members.

A plurality of second ventholes 72, each having a diameter of, e.g.,about 4 mm, is formed between the platform 76 and the slit 68 on thetable 48. Further, ventholes 74 are formed at a bottom portion of thesupporting housing 70. As described above, a clean gas in the inlet sidetransfer chamber 10 is introduced into the closed space inside theclosed hood 50 through the first ventholes 58. The clean gas introducedinto the closed space passes through the cassette 18A on the platform 76and then flows into the supporting housing 70 under the table 48 throughthe second ventholes 72. Thereafter, the clean gas is discharged throughthe ventholes 74 formed at the bottom portion of the supporting housing70 to an outside of a facility.

As illustrated in FIGS. 2 to 4 and FIG. 6, a driving unit 84 foroperating the hood 50 is attached to a side plate 82 of the port 12Aside of the supporting housing 70 under the table 48. The driving unit84 includes an actuator, e.g., a rotary cylinder operated by compressedair, and rotates a driving axis 86 forwardly and reversely. Further, alink mechanism connected to the driving axis 86 will be described later.A solenoid valve 92 is connected to the driving unit 84 via an air tube90 (see FIG. 6) in which a speed controller 88 as an air flow controlleris installed. A control signal from a host computer 110 is inputted intothe solenoid valve 92 via a cable 94. By switching the solenoid valve 92under a control of the host computer 110, the compressed air isselectively introduced into and discharged from the driving unit 84.Further, the host computer 110 monitors and controls an entire operationof a semiconductor processing system.

Provided at the driving axis 86 is a break 93 having, e.g., anelectronic break. The break 93 is controlled by a control signalinputted via a cable 96. The control signal is inputted from, e.g., thehost computer 110 serving as a break controller.

A box-shaped break cover 98 is provided to cover the entire break 93. Aventhole 100 is formed at the side plate 82 (see FIG. 2) and the frontpanel 52, which is open to communicate with inside of the break cover98. Further, formed at a lower portion of the break cover 98 is a gaschannel 102 communicating with an inside of the supporting housing 70.The clean gas in the inlet side transfer chamber 10 is introduced intothe break cover 98 through the venthole 100 and discharged therefromthrough the gas channel 102. By passing the clean gas through the breakcover 98, particles generated therein are discharged downwardly.Further, since the gas channel 102 is positioned below a lower portionof the hood 50 in an open position (see FIG. 4), particles generatedfrom the break 93 are not adhered to the inner surface of the hood 50.

An arc-shaped driving unit cover 99, the arc having an opening angle ofabout 90 degrees, is installed in the supporting housing 70 to fullycover the driving unit 84 and the break cover 98. An upper portion ofthe driving unit cover 99 is fixedly attached to a backside of the table48. A lower portion of the driving unit cover 99 is downwardly open sothat particles can be discharged downwardly. The aforementioned secondventholes 72 formed on the table 48 are provided between a portionattached to the driving unit cover 99 and the slit 68 for allowing thehood 50 to pass therethrough (see FIG. 4).

As depicted in FIG. 2, a micro switch 104 is provided at a positionslightly below a lower portion of the hood 50 when the hood 50 is in theclosed position in the supporting housing 70. The micro switch 104 isused for checking whether or not the hood 50 is in the closed position.

As illustrated in FIGS. 5A to 6, a pair of protection plates 106 isprovided at both sides of the table 48 to cover both sides of the hood50 in the closed position while having narrow gaps therebetween. Inorder to prevent an operator from putting a hand and the like betweenthe hood 50 and the protection plates 106, following safety measures areperformed. In other words, as illustrated in FIG. 6 and the like, aline-shaped light transmitting part 108A and a line-shaped lightreceiving part 108B facing each other are provided at the pair ofprotection plates 106, respectively. The light transmitting part 108Aand the light receiving part 108B included in an obstacle sensor 108immediately stop a rotation of the hood 50 by operating the break 93when an obstacle (e.g., a hand of an operator and the like) is detectedduring a closing operation of the hood 50.

FIGS. 7A to 7D offer diagrams for explaining operations of the drivingunit 84 and the break 93 when the hood 50 is opened or closed in theport structure 16A. The host computer 110 switches a port of compressedair of the solenoid valve 92 in accordance with a process sequence,thereby switching the compressed air with respect to the driving unit 84of the hood 50. In this case, as illustrated in this example, there areprovided three switching types of the port, i.e., a closing operation,an opening operation and maintenance of status quo. Further, when asignal for indicating a presence of an obstacle is received from theobstacle sensor 108, the host computer 110 also serving as the breakcontroller operates the break 93. A detailed description of suchoperation will be followed later.

FIG. 8 is a side view showing a link mechanism for opening and closingthe hood in the port structure shown in FIG. 2. FIGS. 9A and 9Brespectively provide a side view and a vertical rear view showing astructure of a portion attached to the hood and its rotation axis in theport structure illustrated in FIG. 2. With reference to FIGS. 8 to 9B,structures of a link mechanism 111 for transferring a rotational drivingforce to the hood 50 and the portion attached to the hood 50 will bedescribed.

As illustrated in FIG. 8, the driving axis 86 (see FIG. 6) connected tothe driving unit 84 is rotatably supported at the side plate 82 viabearings 112 and fixed members 114. In the same way, a rotational axis116 supporting the hood 50 is rotatably supported at the side plate 82via bearings 118 and fixed members 120 (see FIGS. 8 and 9B). The linkmechanism 111 is installed so as to connect the driving axis 86 with therotation axis 116. The link mechanism 111 transfers the rotationaldriving force of the driving axis 86 to the rotation axis 116.

As shown in FIGS. 9A and 9B, the hood 50 is rotatably attached to therotation axis 116 via a pair of the bearings 122 and a pair of the fixedmembers 124 fixed on an angled portion of the hood 50. Fixed on therotation axis 116 is a pair of rotation arms 126 extending along bothsides of both end portions of the hood 50 while having gapstherebetween. In other words, the rotation arms 126 and the rotationalaxis 116 rotate together as a single body.

A pair of gusset plates 128 is fixed on the hood 50 to face each otherat an opposing position to the rotation arms 126. Resilient members 130including a plurality of coil springs having a length of, e.g., about 45mm are disposed between the gusset plates 128 and the rotation arms 126.In case an external force is applied to the hood 50, a distance betweenthe gusset plates 128 and the rotation arms 126 can be slightlyshortened by a stroke compressing the resilient members 130. In otherwords, the hood 50 can rotate toward the rotation arm 126 by as much asthe stroke.

Hereinafter, a schematic flow of the wafer W in an operation of thesemiconductor processing system illustrated in FIG. 1 will be described.

First, the cassette 18A accommodating therein unprocessed semiconductorwafers W is mounted on the table 48 in one of the three port structures16A to 16C, e.g., the port structure 16A. Thereafter, the hood 50 isautomatically operated toward a closing direction to cover the entirecassette 18A. Next, the sliding door 20A that is closing the port 12A isopened to unload an unprocessed wafer W from the cassette 18A. At thistime, by operating one transfer arm of the second transfer unit 22,e.g., the transfer arm 32, the pick 32A receives and holds the wafer Wfrom the cassette container 18C. Then, by moving the second transferunit 22 in X direction, the wafer W is transferred to the orienter 26.

Thereafter, an unprocessed wafer W, which is previously arranged inposition in the orienter 26, is unloaded from the rotatable table 28 toempty the rotatable table 28. To do so, the other empty transfer arm 34is operated so that the pick 34A receives and holds the wafer W from therotatable table 28.

Next, the unprocessed wafer, which is held by the pick 32A of thetransfer arm 32, is mounted on the empty rotatable table 28. The waferis positioned until another unprocessed wafer is transferred.Thereafter, the unprocessed wafer, which is unloaded from the rotatabletable 28 to the other transfer arm 34, is moved to one of the twoload-lock chambers 8A and 8B, e.g., the load-lock chamber 8A, by movingthe second transfer unit 22 in the X direction.

Then, the load-lock chamber 8A whose inner pressure is alreadycontrolled is opened by opening a gate valve G7. Further, a processedwafer on which a predetermined process, e.g., a film forming process, anetching process or the like, has been performed in the processingapparatus is supported while waiting in the load-lock chamber 8A.

Thereafter, by operating the empty transfer arm 32, the processed waferW waiting in the load-lock chamber 8A is unloaded by the pick 32A. Next,by operating the other transfer arm 34, the unprocessed wafer W, whichis held by the pick 34A, is loaded into the load-lock chamber 8A. Then,the processed wafer is restored to a primary cassette by the secondtransfer unit 22.

Meanwhile, after the unprocessed wafer Wd is loaded into the load-lockchamber 8A, the load-lock chamber 8A is airtightly sealed by closing thegate valve G7. Next, after a pressure is controlled by evacuating aninside of the load-lock chamber 8A, the load-lock chamber 8A is made tocommunicate with the common transfer chamber 6 with a vacuum atmospherealready formed therein by opening the gate valve G7. Then, theunprocessed wafer W is loaded into the common transfer chamber 6 by thefirst transfer unit 14. Since the first transfer unit 14 has the twopicks 14A and 14B, in case the first transfer unit 14 holds a processedwafer, the processed wafer is exchanged for an unprocessed wafer.

Next, required processes are sequentially performed on the unprocessedwafer W in, e.g., each of the processing apparatuses 4A to 4D. When allthe required processes are completed, the processed wafer W is restoredto a primary cassette along the same path as described above in areverse sequence. In this case, the processed wafer W can pass througheither one of the two load-lock chambers 8A and 8B.

Hereinafter, a specific operation in the port structure 16A will bedescribed with reference to FIGS. 10A to 10J. FIGS. 10A to 10J offerdiagrams for schematically explaining an operational relationshipbetween the sliding door 20A and the hood 50 in the port structure 16A.

First, in an initial state, both the sliding door 20A and the hood 50are in a closed state, as illustrated in FIG. 10A. Then, when thecassette 18A accommodating therein unprocessed wafers W is transferredthereto, the hood 50 rotates approximately 90 degrees to thereby belocated under the table 48, as illustrated in FIG. 10B. Thereafter, asillustrated in FIG. 10C, the cassette 18A is installed on the table 48.

After the cassette 18A is completely installed, the hood 50 is rotatedback approximately 90 degrees to cover the entire cassette 18A, asillustrated in FIG. 10D. Next, as shown in FIG. 10E, the sliding door20A is lowered to open the port 12A. Then, as depicted in FIG. 10F, theunprocessed wafers W are sequentially loaded into a processing systemvia the open port 12A by using the transfer arm 32(34) to thereby starta process. At this time, the unprocessed wafers are sequentiallyreceived while the progress of the processing on a previously receivedwafer being monitored to check for its completion. A processed wafer isrestored into the primary cassette 18A. During that time, an open stateof the port 12A is maintained with the sliding door 20A being lowered,as illustrated in FIG. 10G.

After the process for every wafer W in the cassette 18A is completed,the port 12A is closed by raising the sliding door 20A, as illustratedin FIG. 10H. Next, as illustrated in FIG. 10I, the hood 50 covering thecassette 18A rotates approximately 90 degrees in the opening directionagain to be located under the table 48. Further, as illustrated in FIG.10J, the cassette 18A accommodating therein the processed wafers W isunloaded from the table 48 for a following process. Thereafter, the hood50 is closed and then returned to a primary state illustrated in FIG.10A. Further, in this state, a next cassette accommodating thereinunprocessed wafers is expected to be loaded.

While the above-described operations are performed, clean air maintainedat a predetermined level of cleanliness forms a downflow in a facilityin which the processing system 2 is installed, as illustrated in FIGS. 2to 4. Moreover, in the inlet side transfer chamber 10, the clean gas(clean air) sent to the blow fan 38 passes through the filter 40 andforms a downflow illustrated by arrow 44 of FIG. 2. By passing throughthe filter 40, the clean gas becomes a clean gas having a higher levelof cleanliness than outside air. Such downflow is discharged from afloor portion as a facility exhaust.

As a result, an inside of the inlet side transfer chamber 10 is in astate of a positive pressure higher than an outer atmospheric pressureby, e.g., 1.3 Pa. Therefore, in case the sliding door 20A is closed, asillustrated in FIGS. 2 and 3A, a clean gas having a high level ofcleanliness constantly flows into the hood 50 via the first ventholes 58formed at the sliding door 20A and the additional panel 54, asillustrated by arrow 142. Further, in case the sliding door 20A isopened, as illustrated in FIG. 3B, the clean gas having the high levelof cleanliness constantly flows into the hood 50 via the port 12A or thefirst ventholes 58 formed at the additional panel 54, as illustrated bythe arrow 142.

Such clean gas introduced into the closed space in the hood 50 directlypasses through the cassette 18A on the platform 76. Thereafter, theclean gas flows into the supporting housing 70 under the table 48 viathe second ventholes 72 and then is discharged through a bottom portionof the supporting housing 70 to an outside of the system. Accordingly,an atmosphere of the clean gas is maintained in the hood 50 or thecassette 18A and, further, a stagnation of an atmospheric gas isprevented by the constantly introduced clean gas. As a result, apossibility of contaminating the wafer with particles is decreased.Besides, an inside of the hood 50 is in a state with a positive pressurein comparison with an outer atmospheric pressure. Thus, even if the gap66 exists between the additional panel 54 and the hood 50, outside cleanair cannot enter into the inside of the hood 50.

The gap 66 is formed between the additional panel 54 and the hood 50 inthe closed state and, further, the slit 68 is set to have a size toprevent the contact with the hood 50. Accordingly, it is possible toprevent particles themselves from being generated due to a contactbetween members. Further, the driving unit 84 under the table 48 iscovered with the driving unit cover 99. Therefore, the particlesgenerated therefrom are not scattered and can be downwardly dischargedwith the flow of the clean gas through a lower opening of the drivingunit cover 99.

In addition, the break 93 is covered with the break cover 98. Further,the clean air in the inlet side transfer chamber 10 is introduced intothe break cover 98 via the ventholes 100 and discharged through the gaschannel 102. Although a large amount of particles are generated from thebreak 93 for stopping a rotation of the hood 50, such particles can beforced to be discharged downwardly without being scattered due to theabove-described configuration. Accordingly, the wafer W can be preventedfrom being contaminated with the particles. Further, since the gaschannel 102 is positioned under a lower portion of the hood 50 in theopen position (see FIG. 4), particles generated from the break 93 arenot adhered to the inner surface of the hood 50.

A cassette sensor 80 (see FIG. 4) is provided at the platform 76 of thetable 48. Therefore, it is possible to detect whether or not thecassette 18A is properly mounted thereon. Furthermore, a wafer sensor 51is installed at an end portion of the platform 76 at the port 12A side.Accordingly, it is possible to detect whether the wafer W is ejectedfrom the cassette 18A installed on the table 48 (see FIG. 2).

Since a mountable and detachable window 64 is provided at the hood 50, amaintenance work for the inner surface of the hood 50 can be performedby separating the window 64 therefrom when necessary. Further, the hood50 is transparent and, thus, it is possible to observe a state of thecassette 18A or a transfer state of the wafer W.

As described in FIGS. 6 and 7A to 7D, a rotation of the hood 50 iscarried out by supplying compressed air toward the driving unit 84. Atthis time, a supply or an exhaust of the compressed air is carried outby switching the solenoid valve 92 in accordance with an instructionfrom the host computer 110. In case of a port position of the solenoidvalve 92 illustrated in FIG. 7A, the hood 50 rotates in a closingdirection. Further, in case of the port position of the solenoid valve92 illustrated in FIG. 7D, the hood 50 rotates in the open direction.

It is assumed that, for example, an operator puts by mistake an obstacle146 such as a hand and the like toward the table 48 when the hood 50rotates in the closing direction as illustrated in FIG. 7B. In thatcase, the sensor 108 detects the presence of the obstacle 146, and thehost computer 110 immediately operates the break 93 in response to thedetection result to immediately stop the rotation of the hood 50.Accordingly, it is possible to improve a safety for the operator and thelike. Further, while operating the break 93, the host computer 110converts the port of the solenoid valve 92 into a neutral port (port formaintaining a current state position), as illustrated in FIG. 7B.Accordingly, the driving unit (air cylinder) 84 is simultaneouslysupplied with compressed air for rotating the hood 50 in the opendirection and that for rotating the hood 50 in the closing direction.

When the compressed air is applied to the driving unit 84 in bothdirections, as shown in FIG. 7C, although the break 93 is released afterremoval of the obstacle 146 and the hood 50 starts to rotate in theclosing direction, the hood 50 does not rapidly rotate at a high speed.In this case, the hood 50 usually starts to rotate at a low speed equalto the speed at the time the rotation in the closing direction isstopped and, accordingly, safety problem is not an issue.

On the contrary, in case the obstacle 146 is detected, if the portposition of the solenoid valve 92 shown in FIG. 7A is maintained, thefollowing issue may develop. Namely, when the break 93 is released afterremoval of the obstacle 146 and the hood 50 starts to rotate in theclosing direction, compressed air of one side in the driving unit (aircylinder) 84 is completely removed. Accordingly, if compressed air issupplied, a large rotational force is suddenly exerted in the closingdirection and the hood 50 starts to rotate suddenly. Therefore, there isa possibility for endangering the operator.

In order to eliminate the possibility for such a danger, in case thesensor 108 detects the presence of the obstacle 146, the host computer110 converts the port of the solenoid valve 92 into the neutral port(port for maintaining the current state position), as illustrated inFIG. 7B. Accordingly, the driving unit 84 is simultaneously suppliedwith the compressed air for rotating the hood 50 in the openingdirection and that for rotating the hood 50 in the closing direction.

By considering a possibility of danger in which the operator is caughtin the hood 50 being rotated in the closing direction, the resilientmembers 130 are interposed between the hood 50 and the portion attachedto the rotational axis 116, as illustrated in FIGS. 9A and 9B. Sinceonly the hood 50 can be slightly rotated by an external force due to ashortening of the resilient members 130, the operator whose hand or thelike is caught therein can easily pull out the inserted hand. Therefore,the safety can be improved from this point as well. Further, when theobstacle sensor 108 detects an obstacle and the micro switch 104 (seeFIG. 2) detects that the hood 50 in the closed state is opened by anexternal force, it is preferable to temporarily stop the second transferunit 22 in the inlet side transfer chamber 10 for safety.

The semiconductor processing system 2 having the port structures inaccordance with the aforementioned embodiment is an example to which thepresent invention is applied. Thus, the present invention can be equallyapplied to other types of semiconductor processing systems. Further, thenumber of the port structures in the semiconductor processing system 2is only an example and, further, can be more than or less than three.

Furthermore, even though a semiconductor wafer as a substrate to beprocessed has been described as an example in the aforementionedembodiment, the present invention can be applied to a glass substrate,an LCD substrate and the like without being limited thereto.

While the invention has been shown and described with respect to thepreferred embodiments, it will be understood by those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims.

1. A port structure for loading and unloading a substrate to beprocessed into and from a semiconductor processing system, wherein aninside of the system is set to have a positive pressure compared to anoutside thereof by a gas supply, the port structure comprising: abulkhead for partitioning the inside and the outside of the system andhaving a port for passing therethrough the substrate to be processed; adoor for opening and closing the port; a table disposed outside thesystem to face the port, wherein the table is provided with a mountregion for mounting thereon an open cassette accommodating therein aplurality of substrates to be processed in multi-levels; a hoodrotatably disposed between a closed position and an open position withrespect to the table, wherein the hood at the closed position forms,together with the bulkhead and the table, a closed space surrounding themount region and the port, the closed space having a size to accommodatetherein the cassette mounted on the mount region, and the hood at theopen position exposes the mount region; a driving unit for rotating thehood; first ventholes formed through at least one of the bulkhead andthe door so as to introduce the gas from the inside of the system intothe closed space; and second ventholes formed through the table so as todischarge the gas out of the closed space.
 2. The port structure ofclaim 1, wherein a leading end portion of the hood at the closedposition is in a noncontact state wherein there exists a narrow gapbetween the leading end portion and a part facing thereto.
 3. The portstructure of claim 1, wherein the driving unit is disposed under thetable and covered with a driving unit cover for preventing particlesfrom being scattered.
 4. The port structure of claim 1, wherein thetable has a slit for passing the rotating hood therethrough, and thehood is located under the table while in the open position.
 5. The portstructure of claim 4, wherein the second ventholes are disposed betweenthe mount region and the slit.
 6. The port structure of claim 1, whereina break for stopping a rotation of a driving axis is disposed at thedriving axis of the driving unit.
 7. The port structure of claim 6,wherein the break is covered with a break cover for preventing particlesfrom being scattered.
 8. The port structure of claim 1, wherein the hoodincludes a mountable and detachable window for maintaining and repairingan inner surface of the hood.
 9. The port structure of claim 1, whereinthe hood is coupled to a transfer member for transferring a drivingforce of the driving unit to the hood via a resilient member, and theresilient member is compressed by an external force exerted to the hoodto allow a distance between the hood and the transfer member to bereduced.
 10. The port structure of claim 6, further comprising a sensorfor detecting a presence of an obstacle disposed near the port and acontrol unit for operating the break when the sensor detects theobstacle.
 11. The port structure of claim 10, wherein the driving unitincludes an actuator operated by a fluid in an opening direction and aclosing direction, and a fluid pressure in both the opening directionand the closing direction is applied to the actuator when the break isoperated.
 12. The port structure of claim 1, further comprising a pairof protection plates standing at both sides of the table to cover bothside surfaces of the hood while maintaining slight gaps therebetween.